The Role of Six Sigma Applications

by Dan Antony, Demand Media

Hundreds of opportunities for defect exist on this circuit board, but Six Sigma roots out the causes.

circuit imprime 2 image by daniel sainthorant from Fotolia.com

Six Sigma is a continuous improvement methodology, one introduced and trademarked by Motorola in 1984. Since then, the U.S. Army, Caterpillar, Xerox and IBM, among thousands of others, have adopted it. Its basic idea is to eliminate variation in product, as variation means defect. Six Sigma was conceived for manufacturing, but other industries (including service and defense) have come to adopt it, to eliminate variation in processes.

Defects Per Million

Six Sigma defines how well a process works by defects per million opportunities (DPMO).

One Sigma means about 69,000 DPMO; thus, satisfactory output is only about 31 percent.

Three Sigma means 66,800 DPMO, or satisfactory output of about 93.33 percent.

Six Sigma means 3.4 DPMO, or satisfactory output of 99.99966 percent; statistically insignificant. So, for example, only 3.4 out of one million circuit boards would malfunction.

Projects

The Six Sigma project focuses on rooting out the causes of those defects and eliminating them. The five-phase Six Sigma project includes: (1) define the problem; (2) measure the variables of the problem--for example, number of defects per million units of product, or number of defects per shift; (3) analyze the results; (4) improve the process; and (5) control the process, such that the variation never reoccurs.

Variation

Where the other significant continuous improvement methodology (called "lean") focuses upon eliminating waste, Six Sigma eliminates waste by eliminating variation, subsequently eliminating defects. This in turn eliminates waste in all its forms, including wasted materials, wasted labor and the waste involved in return logistics (paying for return shipping). Six Sigma is not as directly focused on the customer as are other continuous improvement methodologies such as lean manufacturing; but, by eliminating defects, it achieves the same goals of lower cost, higher quality and customer satisfaction.

Design

Design for Six Sigma (DFSS) is a systematic methodology to launch a process at the Six Sigma level. The theory is to design a product or process to eliminate any variations to begin with. DFSS treats the design engineering phase as a Six Sigma project, one in which there is inherent waste and variation which must be rooted out.

Lean Six Sigma

Lean Six Sigma (LSS) combines the methodologies of lean and Six Sigma. Lean is a faster, more agile methodology. It involves employees at all levels to identify and eliminate waste. A simple example is that a warehouse worker may observe that the fastest-selling product is located far from the shipping dock. Shelving it right by the shipping dock eliminates wasted movement, wasted labor and wasted fuel. A manager can authorize that change immediately; a months-long Six Sigma project would be overkill for that obvious need.

However, Six Sigma is better suited to rooting out more complex, hard-to-pin-down problems, such as parts defects, or decreasing levels of customer retention. The causes may not be obvious, requiring the measurement and analysis of Six Sigma.

Six Sigma also requires more extensive training in which project managers (called Black Belts and Master Black Belts) are trained and certified in such methods as measurement theory, statistical analytics and design theory.

"The New Six Sigma: A Leader's Guide to Achieving Rapid Business Improvement"; Matt Barney and Tom McCarty; 2003

"Design for Six Sigma"; Greg Brue and Robert G. Launsby; 2003

About the Author

Dan Antony began his career in the sciences (biotech and materials science) before moving on to business and technology, including a stint as the international marketing manager of an ERP provider. His writing experience includes books on project management, engineering and construction, and the "Internet of Things."

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